You know those commercials that show those poor, sad, abandoned animals just looking for a home? Well, in Trigonometry Land they could have those same commercials for poor, sad, forgotten angles.
The special triangles and their angles have been getting all of the love so far, so it's time to branch out and include more. With the addition and subtraction formulas, we can reach out to a bunch of those previously abandoned angles (those poor things) that we never knew how to work with without our handy dandy calculators.